MILAN (Reuters) - Juventus have won 12 out of their 13 games in all competitions this season but coach Massimiliano Allegri said he was still worried that "drops in intensity" could cost his team an eighth successive Serie A title.

Allegri was clearly concerned about last week's 2-1 win at lowly Empoli where Juventus needed a contentious penalty and a moment of individual brilliance from Cristiano Ronaldo to turn the game around after trailing at halftime.

"We can't afford to drop points along the way," said Allegri, whose side lead Serie A by eight points from Inter Milan and Napoli and host Cagliari on Saturday.

"We've had dangerous drops in intensity which could cost us the championship. We need to show great respect and keep our concentration high to win these games, which you can only win on the pitch."

He reminded reporters that winning should never be considered routine.

"You saw how much trouble we had against Empoli, it shows that winning is never easy," he said. "For our opponents, winning against Juventus is always a big achievement."

"Cagliari are difficult opponents," he added. "They are the team which run the most in the championship and are very dangerous in the area."

Allegri said that defender Giorgio Chiellini and midfielder Federico Bernardeschi were not fully fit and would sit out the match, while Sami Khedira and Mario Mandzukic would be available for selection.

Miralem Pjanic and Blaise Matuidi would play in midfield alongside either Rodrigo Bentancur or Juan Cuadrado.

Left back Alex Sandro would be rested and right back Joao Cancelo would return to the side, he said. Juventus have conceded seven goals in 10 league games so far which Allegri said was too many. "It puts us on course to concede more than 30 goals in the season, and if you concede that many, you won't win the league," he said.

(Reporting by Brian Homewood; editing by Martyn Herman)

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